Natural Selection Lab- PhET Simulation

Pre-Lab Questions

  1. What variables can you influence in this lab?

Colors, long/short teeth, long/short tail, environment, adding wolves and food

  1. Define what a genetic mutation is. How do genetic mutations happen? How often?

Genetic mutation is happened randomly when a factor in the dna is changed so it is different from its parent cells.

  1. What do the terms fitness and adaptation mean? What is the difference between the two?

Adaptation is when a species change their behavior to better suit the environment while fitness the degree of suitability in a particular environment

  1. What selection factors might effect an animal population besides the ones used in this lab?

Their height, behavior, and food preference

Designing The Experiment

In this Lab you will be controlling the mutations and environment of a population of rabbits. Your will create three hypotheses and design an experiment to test each one. Your hypothesis will follow the format where you fill in the (...) with your own ideas and reasons.

I hypothesize that brownrabbits will be more likely to survive under their brown fur within the equator environment, because they can hide better from predators

I hypothesize long tail rabbits that will be more likely to survive under their fur within the arctic tundraenvironment, because they can survive better in the cold

I hypothesize that long teeth rabbits will be more likely to survive under long teethwithin the equatorenvironment, because they can find food better

***You must make at least one hypothesis for each of the three different types of phenotype mutations***

For each experiment you must have a control (no mutation) and fill in the following chart

Experiment
and
Hypothesis / Pheno
type / Selective Factor / CONTROL
Group
Initial Population at F3 / CONTROL
Group
Final Population / Experment
Group
Initial Population at F3 / Experiment
Group
Final Population / Conclusion/
Observation
Brown fur bunnies will be more than the white ones. / Brown fur is dominant, white fur is recessive / Brown fur / 5 / 2 / 1 / 70= total bunnies
68= brown
2= white / Brown fur bunnies survived more than the white ones in the equator area
Long tail bunnies will have a higher adaptability than short tailed bunnies / Long tail is dominant, short tail is recessive / Long tail / 6 / 110 / 0 / 128= total bunnies
110= Short tail
18= Long tail / The hypothesis is wrong, at the end the short tail is more dominant compared to the long ones.
Long teeth will be have a higher chance to survive so they can find food easily / Long teeth is dominant, short teeth is recessive / Long Teeth / 5 / 13 / 1 / 18=Total Bunnies
13= Short Teeth
5= Long Teeth / The long teeth is more recessive compared to the long ones.

•For each of the experiments, begin by adding a friend and a mutation. Wait until the F3 generation before adding the selective factor. After adding the selective factor let the simulation run for another 3 or 4 generations.

•Use the population numbers from the chart to get you numbers for the table, remember you can zoom in and out on the chart to get more accurate reads.

•Repeat for experiments 2, 3 and 4

Post-Lab Questions

  1. Based upon your evidence from the simulation what conclusion are you able to make about each of the three different types of phenotypes in rabbits?

The most significant phenotype is the fur color, since it is the main factor that helped them hide from the predators. Hence, it is why rabbits with fur that have the same color as the environment would survive better than those with different fur color.

  1. What happens to animals that cannot compete as well with other animals in the wild?

They will eventually die out either from lack of food or eaten by predators.

  1. Sometimes animals that are introduced into an area that they never lived in before, out-compete and endanger resident species, why do you think this happens?

Because their behavior is not yet suited for the environment so they can’t coexist with the residential species since their behavior contradicts one another.

  1. If only one species is considered the "fittest", why do we still have so many variations among species. Why do some birds have very long pointy beaks, while other birds have short flat beaks?

Because each attributes only work for specific environments and is designed to help the animals survive in that environment.

  1. How do you think diseases can affect natural selection?

Eventually, a species would develop an immunity against the disease, which helped them survive while other species died out.

  1. How does this simulation mimic natural selection? In what ways does this simulation fail to represent the process of natural selection?

It mimics the way a predator would prefer eating a prey that they can easily spot. However, it fails to consider other factors such as diseases, natural disaster, and other predators that have specific traits to help them spot their prey easier.

Extension- Changing the Dominance and Recessive Alleles

Take one of the experiments from the lab. Recreate the same experiment, EXCEPT when you add the mutation EDIT THE GENES by switching the dominant and recessive allele for that trait. Make a hypothesis, fill in the chart again and compare the results to your initial experiment.

Experiment
and
Hypothesis / Pheno
type / Selective Factor / CONTROL
Group
Initial Population at F3 / CONTROL
Group
Final Population / Experment
Group
Initial Population at F3 / Experiment
Group
Final Population / Conclusion/
Observation
If the brown fur trait is recessive, the rabbit population will decline / Brown fur / Wolves / 17 / 3 / 1 / 0 / The brown rabbit died because it’s gene is recessive, while the white rabbit who are left are finished by the wolves.
  1. Did switching the alleles for dominant and recessive have any impact on the population of rabbits? If so Why? In nothing changed Why not?

If the dominant trait is a trait that can help them survive better, then the population of rabbit will continue to increase. However, if the trait that help them survive better is recessive, it will be hard for them to survive.

  1. Two parent rabbits are both heterozygous for the trait. Create Punnet squares for the original experiment and the new experiment (with the changed alleles). What are the phenotype ratios of the Punnet squares? Does this evidence support your finding? and how? B= Dominant b= recessive

B / b
B / Bb / Bb
b / Bb / bb

Dominant: 75%Recessive: 25%

This evidence supports the fact that recessive genes shows up less likely than dominant genes, hence if the adaptability trait is a recessive gene, it will show up less likely. However, the gene would always be carried if both parents are heterozygous, increasing the chance of an offspring to get the trait to survive.

  1. If this new experiment were to run longer would the end result be the same or different from the original experiment?

It would end the same since if the adaptive trait is the recessive gene, the majority of the population would still decline.

Extension- Working with Pedigrees-Switch from the population chart to the pedigree chart

Begin by adding a friend and a mutation. Wait until the F5 generation. Copy the Pedigree for two rabbits (described below) using the key. Assume that male rabbits are on the left and female rabbits are on the right.

Find these two rabbits, make sure they have at least four generations:

  1. Select a rabbit that has the mutation.
  2. Select a rabbit without the mutation but with parents or grandparent with the mutation.

Answer the following questions:

  1. How could using a pedigree be helpful?

We can use the pedigree to know the rabbit’s ancestor to figure out where the genetic mutation happens.

  1. What does it mean to have a yellow triangle above the rabbit?

It means the rabbit is the one that started the mutation.

  1. What does it mean when a rabbit has a red X over it?

That means the rabbit have the recessive gene but doesn’t show the trait.

  1. How accurate are the pedigrees used in this lab? Did each couple only have one baby?

It is not really accurate since the couple only have one baby while in reality rabbits have multiple babies.